I am new to ubuntu and i would like some help.
I have a laptop with windows 7 installed but i would love to have ubuntu too because it's a great OS.
So i would like to install ubuntu on an external usb hard drive (320 - 500 GB) and i have some questions about that :

Do i need a usb external hard drive which will be compatible with ubuntu - linux ? or i can do it with any hard drive

If i make a partition on it for ubuntu staff will i be able to use it and save other staff in the usb hard drive (movies,songs,documents etc) ?

If i have ubuntu installed on the usb hard drive will i be able to boot ubuntu from any pc ?

Are my changes going to be saved normally or my settings will be lost after shut down ?

Waiting for your answers, if something is not explain well tell me to try explain it better .
Thank you!

Of course! Answer me one last thing please ... is it going to have a normal speed or is it going to be slow ? my laptop has only 2.0 usb ports..
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user156097May 13 '13 at 12:06

It's going to be slower. But that depends on what you are doing. It's acceptable. Once you get used to interface you can repartition your internal HD to include Ubuntu (20 GB is more than enough for Ubuntu and swap + what you need for data).
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IvanPMay 13 '13 at 15:03

There are a few technical considerations of which you need to be aware.

First, any computer that uses this needs to be able to boot from USB.
So you will need to check the BIOS and make sure that the computer is
capable of using it.

Second, unless your drive and computer are both USB 3 capable, the
end experience might be so slow and cumbersome that it is only useful
in an emergency.

All in all, you'd be better off using eSATA if it is available. I am not trying to discourage experimentation, but an external eSATA drive will be pretty much like using an internal HD and you'll almost certainly be satisfied with the final results.

My laptop can boot from usb but can you be a little more specific in the usb 3.0 thing ? My laptop has only usb 2.0 ports so you are saying that it will be very slow in that case ?
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user156097May 12 '13 at 9:06

I have done this, my laptop is only USB2 compatible (old laptop) but Ubuntu runs just fine. Obviously USB3 would be an improvement for moving data from/to the disk, but must of my apps run in the RAM, so if you've got enough RAM (>= 1 GB) you are good to go.
–
edwinJun 6 '13 at 2:21